Examples of Shadow Effects

PPK[a_,b_,c_]:=Module[{ppt,pps},
ppt=Table[{c*Sin[a*t]^2,b*Cos[b*t]^3,
a*Sin[c*t]*Log[t+1]},{t,0,6Pi,.05}];
pps=GeometricTransformation[Tube[ppt,.1],
RotationTransform[Pi,{0, 0, 1}]];
Show[Graphics3D[{FaceForm[{Darker[Gray],Opacity[.3]}],pps}],
Graphics3D[{FaceForm[{Blue,Opacity[.9]}],Tube[ppt,.1]}],
Boxed->False,Background->RGBColor["silver"],
AspectRatio->1,ImageSize->500]];
PPK[4,3,2]

PPTS:=Function[{a,b,c},
img=Graphics3D[{RGBColor["#3636ff"],
Tube[Table[{c*Sin[a*t]^2,b*Cos[b*t]^3,
a*Sin[c*t]*Log[t+1]},{t,0,6Pi,.03}],.1]},
Boxed->False,AspectRatio->1,PlotRange->All,
ImageSize->{600,500},Background->RGBColor["silver"]];
ImageCompose[Lighter@Blur[img,10],SetAlphaChannel[img,
ColorNegate[img]],Scaled[{.38,.52}]]]
PPTS[4,3,2]